The primary objective of this research is to delineate the role of various prostaglandins in circulatory control, how prostaglandins and the renin-angiotensin system interrelate, and the respective contributions of these two hormonal systems to regulation of vascular tone in hypertension. Experiments on anesthetized dogs are designed to determine the mechanism of renal vasodilator action of converting enzyme inhibitors, the relative role of intrarenal and extrarenal converting enzyme inhibition in this action, and the interaction of these agents with renal prostaglandins. The comparative role of prostaglandin E and prostacyclin in regulation of renal hemodynamics in the low salt state and during renal ischemia is also being sought.